Complex interaction of sensory and motor signs and symptoms in chronic CRPS.

Spontaneous pain, hyperalgesia as well as sensory abnormalities,
autonomic, trophic, and motor disturbances are key features of
Complex Regional Pain Syndrome (CRPS). This study was conceived to
comprehensively characterize the interaction of these symptoms in
118 patients with chronic upper limb CRPS (duration of disease:
43±23 months). Disease-related stress, depression, and the degree
of accompanying motor disability were likewise assessed. Stress and
depression were measured by Posttraumatic Stress Symptoms Score and
Center for Epidemiological Studies Depression Test. Motor
disability of the affected hand was determined by Sequential
Occupational Dexterity Assessment and Michigan Hand Questionnaire.
Sensory changes were assessed by Quantitative Sensory Testing
according to the standards of the German Research Network on
Neuropathic Pain. Almost two-thirds of all patients exhibited
spontaneous pain at rest. Hand force as well as hand motor function
were found to be substantially impaired. Results of Quantitative
Sensory Testing revealed a distinct pattern of generalized
bilateral sensory loss and hyperalgesia, most prominently to blunt
pressure. Patients reported substantial motor complaints confirmed
by the objective motor disability testings. Interestingly, patients
displayed clinically relevant levels of stress and depression. We
conclude that chronic CRPS is characterized by a combination of
ongoing pain, pain-related disability, stress and depression,
potentially triggered by peripheral nerve/tissue damage and ensuing
sensory loss. In order to consolidate the different dimensions of
disturbances in chronic CRPS, we developed a model based on
interaction analysis suggesting a complex hierarchical interaction
of peripheral (injury/sensory loss) and central factors
(pain/disability/stress/depression) predicting motor dysfunction
and hyperalgesia.